Metal cutting tool



1946. c. E. NORDSTROM METAL CUTTING TOOL Filed Jan. 29, 1945 INVENTOR CARL E. NORDSTROM ATTORNEY Patented Nov. 12, 1946 METAL CUTTING TOOL Carl E. N ordstrom, Evanston, Ill., assignor to Teletype Corporation, Chicago, 111., a corporation of Delaware Application January 29, 1945, Serial No. 575,137

1 Claim.

This invention relates to metal cutting tools and more particularly to burring or counterboring and countersinking devices.

The principal object of the invention is to provide a metal cutting device for simplifying the execution of certain metal cutting operations.

Another object of the invention is to provide a burring tool which comprises a retractable cutting element which is susceptible of being ejected by camming action automatically upon forcing the tool into cutting position.

Specifically, the burring tool comprising a shank, cutting element, compression spring and collar is clamped in a drill chuck or similar holding device in a lathe or drill press. The piece part to be burred is held in a suitable fixture and as the burring tool is piloted through the hole, the edge of which is to be burred, the cutting element is held in retracted position by a spring, compressed between the cutting element and the shank portion. Then, as pressure is applied to force the cutting element into the hole to be burred, the cutting element, due to the camming action between the edge of the hole and a rounded corner of the cutting element, will be cammed forward to countersink or counterbore the hole in the piece part. With the device, according to the present invention, countersinking or burring operations which were heretofore inaccessible and dllTlClllt of execution are rendered more readily accessible.

The foregoing objects and features of the invention will appear from the following detailed description taken in conjunction with the accompanying drawing, in which Fig. 1 is an elevational view of the arrangement according to the present invention;

Fig. 2 is a top view of the device substantially as shown in Fig. 1, and

Fig. 3 is a vertical sectional view taken approximately on line 3-3 of Fig. 2.

Having reference to the drawing, a spindle or shank H is adapted to be clamped in a drill chuck (not shown) or similar holding device in a lathe or drill press. A U-formed piece part l2 to be burred is held in a suitable fixture (not shown), appropriately placed on the table of the drill press. The shank H is recessed or slotted at It! to receive, slidably therein, a cutting element or blade l4. Blade I4 is provided with a forwardly attending portion I 5 which terminates in a cutting edge l6, which portion extends through an aperture IT in shank H which connects with the recess l3. Of course, the projection l5 may be round or square or of any geometrical conformation. Furthermore, the cutting edge may be conformed or shaped to produce a countersink, or it may be shaped to produce a counterbore, if desired.

A compression spring I 8 is positioned in the recess 13 and is seated in spring seats [9 and 2| in the shank II and element l4, respectively. In this manner, the spring [8 normally tends to eject the element I4 and. to maintain said element M in its protruded position, as shown in Fig. 3. A collar 22 is adjustab-ly mounted on shank H by means of a set screw 23. Collar 22 is provided with a groove 24 joining its central opening to receive the element l4. Collar 22 thus restricts or limits the movement of blade M. The edge of element [4 is appropriately curved at 25 to provide a camming surface.

In the operation of the arrangement according to the invention, the pilot 26, forming the lower end of the shank II, is caused to be projected through the hole to be burred. Then, as pressure is applied to shank H to force the blade [4 further into the piece part [2, the blade l4, due to the camming action between shoulder 27 of the piece part [2 and curved portion 25 of blade M, will be cammed forward to the dotted position shown in Fig. 1, to countersink and burr the piece part l2 at 28. It is observed that thev collar 22 is independently adjustable along the shank I l and not only restricts or limits the movement of blade l2, but also, it gauges the depth of countersinking as determined by its position on the shank I I. By advancing or adjusting the collar 22 toward the end of the pilot 26, the aperture in the piece part I2 is countersunk to a lesser degree than if the collar 22 were shifted or adjusted in the opposite direction. The device according to the invention facilitates the burring of the inner sides of U-formed piece parts.

The embodiment described herein is considered to be illustrative and not restrictive, and accordingly, all modifications are contemplated which come within the spirit and scope of the appended claim.

What is claimed is:

In a burring tool, a rotatable cutter-carrying member comprising a shank adapted to be inserted through a hole in the work, a retractable cutter reciprocably mounted in a slot in said shank, said cutter provided with a cam contour, a collar adjustably carried on said shank and grooved to receive said cutter in retracted position, and spring means for yieldably retaining said cutter in said groove between said shank and said collar, said spring means thereby normally acting to retract said cutter and urge itagainst said collar, whereby upon the cooperation of said cam contour with said work when the tool is forced into cutting position said cutter is automatically ejected by the camming action between said cam contour and said work. CARL E. NORDSTROM. 

